New functions for converting path name.

["Shigio Yamaguchi" <shigio tamacom com>]

Hello,

I have made two library functions and its test suite for glib.
G_abs2rel(3) make a relative path name from an absolute path.
G_rel2abs(3) make an absolute path name from a relative path.
I think it is useful as part of glib library. What do you think?

The package is here.

	http://www.tamacom.com/pathconvert/glibpath.tar.gz

You can build and test this package like this:

## BUILD
% make
cc -I/usr/local/include -c grel2abs.c
cc -I/usr/local/include -c gabs2rel.c
ar -cq libpath.a grel2abs.o gabs2rel.o
%

## TEST
% make test
chmod u+w t
(cd t; make test)
cc -o rel2abs rel2abs.c ../libpath.a
cc -o abs2rel abs2rel.c ../libpath.a
perl ./test.pl
TEST start .......................................................... COMPLETED.
%

Here is the manual. Thank you in advance.
-------------------------------------------------------------------------------
NAME
     g_abs2rel - make a relative path name from an absolute path

SYNOPSIS
     char *
     g_abs2rel(const char *path, const char *base, char *result, size_t size);

DESCRIPTION
     The g_abs2rel() function makes a relative path name from an absolute path
     name path based on a directory base and copies the resulting path name
     into the memory referenced by result.  The result argument must refer to
     a buffer capable of storing at least size characters.

     The resulting path name may include symbolic links.  The g_abs2rel()
     function doesn't check whether or not any path exists.

RETURN VALUES
     The g_abs2rel() function returns relative path name on success.  If an
     error occurs, it returns NULL.

ERRORS
     The g_abs2rel() function may fail and set the external variable errno to
     indicate the error.

     [EINVAL]           The base directory isn't an absolute path name or the
                        size argument is zero.

     [ERANGE]           The size argument is greater than zero but smaller
                        than the length of the pathname plus 1.

EXAMPLE
         char result[MAXPATHLEN];
         char *path = g_abs2rel("/usr/src/sys", "/usr/local/lib", result, MAXPATHLEN);

     yields:

         path == "../../src/sys"

     Similarly,

         path1 = g_abs2rel("/usr/src/sys", "/usr", result, MAXPATHLEN);
         path2 = g_abs2rel("/usr/src/sys", "/usr/src/sys",
						result, MAXPATHLEN);

     yields:

         path1 == "src/sys"
         path2 == "."


BUGS
     If the base directory includes symbolic links, the g_abs2rel() function
     produces the wrong path.  For example, if '/sys' is a symbolic link to
     '/usr/src/sys',

         char *path = g_abs2rel("/usr/local/lib", "/sys", result, MAXPATHLEN);

     yields:

         path == "../usr/local/lib"         /* It's wrong!! */

     You should convert the base directory into a real path in advance.

         path = g_abs2rel("/sys/kern", realpath("/sys", resolvedname), result,
     MAXPATHLEN);

     yields:

         path == "../../../sys/kern"        /* It's correct but ... */

     That is correct, but a little redundant. If you wish get the simple an-
     swer 'kern', do the following.

         path = g_abs2rel(realpath("/sys/kern", r1), realpath("/sys", r2),
                                             result, MAXPATHLEN);

     The realpath() function assures correct result, but don't forget that
     realpath() requires that all but the last component of the path exist.

SEE ALSO
     g_rel2abs(3)

AUTHORS
     Shigio Yamaguchi (shigio tamacom com)

-------------------------------------------------------------------------------
NAME
     g_rel2abs - make an absolute path name from a relative path

SYNOPSIS
     char *
     g_rel2abs(const char *path, const char *base, char *result, size_t size);

DESCRIPTION
     The g_rel2abs() function makes an absolute path name from a relative path
     name path based on a directory base and copies the resulting path name
     into the memory referenced by result.  The result argument must refer to
     a buffer capable of storing at least size character

     The resulting path name may include symbolic links.  g_abs2rel() doesn't
     check whether or not any path exists.

RETURN VALUES
     The g_rel2abs() function returns absolute path name on success.  If an
     error occurs, it returns NULL.

ERRORS
     The g_rel2abs() function may fail and set the external variable errno to
     indicate the error.

     [EINVAL]           The base directory isn't an absolute path name or the
                        size argument is zero.

     [ERANGE]           The size argument is greater than zero but smaller
                        than the length of the pathname plus 1

EXAMPLE
         char result[MAXPATHLEN];
         char *path = g_rel2abs("../../src/sys", "/usr/local/lib", result,
     MAXPATHLEN);

     yields:

         path == "/usr/src/sys"

     Similarly,

         path1 = g_rel2abs("src/sys", "/usr", result, MAXPATHLEN);
         path2 = g_rel2abs(".", "/usr/src/sys", result, MAXPATHLEN);

     yields:

         path1 == "/usr/src/sys"
         path2 == "/usr/src/sys"

SEE ALSO
     g_abs2rel(3)

AUTHORS
     Shigio Yamaguchi (shigio tamacom com)
-------------------------------------------------------------------------------
--
Shigio Yamaguchi - Tama Communications Corporation